Rock drill with overriding clutch

ABSTRACT

A FLUID ACTUATED ROCK DRILL OF THE PERCUSSIVE TYPE IS PROVIDED WITH AN OVERRIDING CLUTCH ADAPTED TO BE ACTUATED BY THE OPERATING FLUID IN TIMED RELATION WITH THE PERCUSSIVE MECHANISM TO ROTATE THE DRILL STEEL.

United States Patent Inventor Jacob E. Feucht Sidney, Ohio Appl. No. 826,516

Filed May 21, 1969 Patented June 28, 1971 Assignee Westinghouse Air Brake Company Wilmerding, Pa.

ROCK DRILL WITH OVERRIDING CLUTCH 5 Claims, 8 Drawing Figs.

[1.8. CI. 173/107, 173/108 Int. Cl E21c 3/24, E21c 3/30 Field Search 173/107, 108

w i e [56] References Cited UNITED STATES PATENTS 871,594 11/1907 Jones 1,176,443 3/1916 Haesler 1,326,245 12/1919 Worthen 1,502,233 7/1924 Curti 2,618,241 11/1952 Larcen etal Primary Examiner-Ernest R. Purser AttorneyJames E. Nilles ABSTRACT: A fluid actuated rock drill of the percussive type is provided with an overriding clutch adapted to be actuated by the operating fluid in timed relation with the percussive mechanism to rotate the drill steel.

PATENTEU JUH28 1971 saw 2 or 3 lure/9m:

/f fH/U/f ROCK DRILL WITH OVERRIDING CLUTCH BACKGROUND It has heretofore been common practice to provide fluid actuated rock drills with means for intermittently rotating the drill steel as the steel is percussively operated.

One such mechanism includesa so-called rifle bar having a stem which is slidably engageable with the fluted bore of the piston which drives the drill steel, the stem having a head within which is disposed a ratchet mechanism.

This ratchet mechanism of the standard rifle bar employs V- shaped notched teeth in the ratchet ring and pawls which pivot on the rifle bar head to lock the rifle bar in one direction while permitting it to rotate freely in the opposite direction.

Since the reciprocating piston is helically splined t the rifle bar, the piston is caused to rotate on its upstroke while the pawls engage the ratchet ring teeth, and on the downstroke, the rifle bar turns to permit the pawls to engage another set of ratchet teeth.

This action occurs about 2,000 times per minute to produce rotation of the piston which, in turn, is transferred to the drill steel through splines and hex-shaped members, and the shock and wear on the various parts is extremely great with the pawls and springs especially being high maintenance items.

SUMMARY It is therefore an object of the present invention to provide mechanism for rotating the drill steel ofa rock drill which obviates the aforesaid disadvantages and objections.

Another object of this invention is to provide improved drill steel rotation mechanism which not only eliminates the drag which is normally produced by rifle bar rotation but which also eliminates the rifle bar per se along with its various attendant parts.

Still another object of the invention is to provide improved means for effecting drill steel rotation which minimizes backlash and in which wear life of the various parts is increased to a maximum extent to thereby effectively reduce maintenance.

A further object of the present invention is to provide an improved overriding clutch operable by a piston powered by the same fluid as is used to operate the drill and at the same cyclic speed for rotating the drill steel independently and without need for a rifle bar or the like.

These and other objects and advantages of the invention will become apparent from the following detailed description.

THE DRAWINGS A clear conception of the several features constituting the present improvements and of the mode of construction and operation of a typical pneumatic rock drill may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

FIG. 1 is a plan view of a typical pneumatically operable rock drill embodying the invention;

FIG. 2 is a central longitudinal section through the drill of FIG. 1;

FIG. 3 is a transverse section taken generally along the line 3-3 of FIG. 1;

FIG. 4 is a schematic view showing a somewhat modified circuitry for actuating the clutch;

FIG. 5 is another schematic view illustrating still another modified circuitry and clutch actuator;

FIG. 6 is a sectional view taken generally along the line 6-6 of FIG. 5;

FIG. 7 is a similar sectional view through a further modified clutch actuating mechanism; and

FIG. 8 is still another schematic view showing the use of a four way valve means for reciprocating the clutchactuator.

DETAILED DESCRIPTION The typical rock drill shown herein as embodying the invention comprises, in general, a generally cylindrical main housing 10 formed with a piston chamber 12 therein. Mounted for reciprocation within the chamber 12 is a piston 14 having a forward extension 16 slidable within the bore 18 of a chuck 20. The chuck 20 is mounted for rotation within a front housing portion 22 of the main casing 10, and slidablyreceived in the front end of the chuck 20 for rotation therewith is the shank portion 24 of a working implement 26. The front face 28 of the piston extension 16 is adapted to impact against the rear face 30 of the implement shank 24 to percussively drive the same.

The working implement is provided with a centrally disposed orifice 34 through which pressure fluid may be admitted in a customary manner to the cutting face of the implement for cleaning the hole being drilled. A valve block 36 is suitably secured within the rear end of the main casing or housing 10 and a fluid actuated valve 38 is reciprocably mounted within this valve block 36 for controlling the admission of pressure fluid to the piston chamber 12 for actuating the piston 14 and percussively driving the working implement 26. The rear of the casing 10 of the drilling machine terminates in a backhead 40, and secured to this backhead 40 in any suitable known manner is a drill manipulating handle 42.

Rotatably confined within the blackhead 40 is a throttle valve 46 formed with a central bore 48 to which pressure fluid is admitted in a customary manner via a flexible hose (not shown). The throttle valve 46 is further provided with a radial orifice 50, and a passage 52 leads from the throttle valve confining bore to an annular recess 54 which, in turn, is in constant communication with the valve 38 through a plurality of passages 56. The piston chamber 12 rearwardly of the piston 14 is intermittently communicable with the passages 56 past the valve 38 via ports 58, the chamber 12 also being intermittently vented to atmosphere by means of passage 60 located within the area ofmovement of piston 14.

A tube 64 is suitably secured within the backhead 40 and this tube extends centrally through the piston 14 and its forward extension 16 into proximity with the rear end of the orifice 34 of the working implement 26. As is customary, the tube 64 is adapted to carry cleaning fluid from the backhead 40 to the cutting face of the implement 26 for the purpose of cleaning the hole being drilledduring operation of the machine.

Since the drilling machine thus shown and described is of conventional well-known construction, it is believed unnecessary to describe the operation in detail. However, when the throttle valve 46 is rotated to position the orifice 50 thereof in communication with the passage 52, as shown, pressure fluid supplied from an air compressor or other suitable source (not shown) is admitted to the valve block 36 and is alternately distributed by the fluid actuated valve 38 to the front and rear of the piston displacement chamber 12 on opposite sides of the piston 14 to actuate the same, the front and rear of the piston displacement chamber being alternately exhausted via passage 60. During reciprocation of the piston 14, intermittent blows are delivered to the working implement 26 by contact of the front face 28 of the piston extension 16 with the rear face 30 of the shank 24 of the implement 26. Also, the hole being worked may be cleaned by admission or pressurized fluid to the rear end of the tube 64 in a conventional manner.

It is also customary practice to provide means for intermittently rotating the working implement or drill steel 26 as it is percussively operated as described. One of the most common rotating mechanisms includes arifle bar or rifled stem which is slidably engageable with a fluted bore in the piston 14. The rifle bar or stem has a head housing a plurality of pawls and plungers cooperable with a ratchet mechanism embracing the head. Thus, by helically splining the reciprocating piston to the rifle bar, it is caused to rotate on its back stroke as the pawls are engaged with the teeth of the ratchet ring, and on the forward stroke of the piston, the rifle bar rotates to permit the pawls to engage another set of ratchet teeth.

However, in accordance with the present invention, the usual rifle bar and its attendant helical splining and actuating mechanism is replaced by a unique overriding clutch arrangement. In the typical example illustrated, the front or forward portion 22 of the main housing or casing is formed to rotatably receive an actuating ring 70 which embraces the enlarged cylindrical portion 72 of the rotatable chuck or sleeve 20, the ring 70 being driven in timed relation with the percussive action of the drill and, in turn, having an overriding clutch connection with the chuck 20 for intermittently rotating the same as hereinafler more fully described.

In the embodiment of FIGS. 1 to 3, the ring 70 is formed with an integral radiating lever or actuating finger 74 which projects laterally into a transverse receiving aperture 76 formed in the small diameter end 78 of the reciprocable piston 80. The piston 78,80 is confined within a displacement chamber 82 formed in a transverse cylindrical portion 84 of the front housing 22 of the drilling machine, the cylindrical portion 84 being closed at its opposite ends in a suitable manner as by means of closure plates 86,88. Thus, reciprocation of the piston 78,80 transmits motion to the lever or actuating finger 74 and causes the ring 70 to rock about its axis in timed relation to the movement of the piston.

The rotating producing piston 78,80 is powered by the same air as is used to operate the drill and this is accomplished by connecting the displacement chamber adjacent one face of the piston 78,80 to the displacement chamber on one side of the drill piston 14, with the displacement chamber adjacent the other face of the piston 78,80 being connected to the displacement chamber on the other side of the piston 14 of the drill. In the example shown, the large area face of the piston 80 is connected via line 90 with the front portion of the chamber 12 while the annular space between the large and small diameters of the piston 78,80 is connected via line 92 with the rear portion of the chamber 12 of the drilling machine. Accordingly, as pressurized fluid is distributed by the fluid actuated valve 38 to the rear portion of chamber 12 to move the piston 14 and drill in a forward direction,the line 92 is open and pressurized fluid forces the piston 78,80 to the right as viewed in FIG. 3, and on the return stroke of the piston 14, the line 90 is opened and pressurized fluid acts on the large area face of the piston 78,80 to force this piston to the left. This action continues as long as the drill is operating, and the reciprocation of the piston 78,80 rocks the ring 70 as hereinabove described.

To transmit motion from the ring 70 to the chuck 20 and working implement 26, the inner surface of the ring 70 is adapted to have one way actuating engagement with the enlarged cylindrical portion 72 of the chuck or sleeve 20. As shown, this actuating engagement consists generally in an annular series of rollers 98 arranged within wedge shaped recesses 100 fonned in the periphery of the enlarged cylindrical portion 72 of the chuck 20, the rollers 98 each being constantly urged toward the reduced end of their respective wedge-shaped recesses 100 as by means of springs 102 compressed within bores 104 and guided for movement as by means of headed guide pins 106.

As shown, the rollers 98 are preferably urged tangentially and somewhat radially within their respective recesses 100 toward the inner peripheral surface of the ring 70, thus causing locking engagement between the ring 70 and cylindrical portion 72 of the chuck 20 upon rotation of the ring 70 in a counterclockwise direction as viewed in FIG. 3 while permitting release of the rollers 98 upon rocking movement of the ring 70 in a clockwise direction, the spring pressed rollers 98 thus cooperating with the ring 70 in the manner of a one way overriding clutch. To facilitate free rotation of the chuck 20, suitable roller bearings 108 or the like may also be provided between the chuck and the housing portion 22, and so that the working implement or tool 26 will rotate with the chuck 20, the shank 24 and the receiving aperture 110 of the chuck 20 are of hexagonal shape.

While the actuating means for the piston 78,80 and the motion transmitting connection between such piston and the ring 70 has thus far been specifically described with reference to the embodiment shown in FIGS. 1 to 3 inclusive, the piston 78,80 may, in fact, be actuated in various optional ways, and this piston may likewise be connected by means of other types of motion transmitting mechanism with the clutch or actuating ring 70. I

For example, the enlarged area end of the actuating piston designated 180 in FIG. 4 may be connected via line I with the rear of the displacement chamber 12 of the drill with the reduced area portion of the piston being connected via line 192 with the forward end of the displacement chamber 12. As a further alternative, the stem or reduced diameter portion 178 of the rotation piston 178,180 of FIG. 4 could be connected to the main air supply continuously to effect return of the piston. In such case, the line 192 would be eliminated and would be replaced by line 194 illustrated by means of dotted lines in FIG. 4. In still another embodiment, the lines 192 and 194 as shown in FIG. 4 could both be eliminated and could be replaced by a return spring compressed betweenthe reduced portion 178 of the piston and the adjacent end wall of the cylinder. In any case, however, the action of the rotation producing piston and its attendant mechanism is as hereinabove described.

FIGS. 5 and 6 illustrate a variation in the rotation piston construction as well as in the actuating connections therefor. In this embodiment, the rotation piston 278,280, is, in effect, formed in two separate pieces, the large piston being identified by the numeral 280 and the small piston by the numeral 278. As shown the small piston 278 contacts the lever rod 74 of the rotation ring 70 on one side and the large piston 280 contacts the lever rod 74 of the rotation ring on the other side. As further shown, the small piston 278 may be placed in communication with a continuous supply of air via line 292 while the large piston is placed in communication with one of the ends of the hammer piston chamber 12 to receive pressure intermittently therefrom. Again, the action of this modified device is the same as hereinabove described.

formed on the small diameter portion 378 of the piston 380.

Thus, as the piston 378,380 reciprocates, its motion is transmitted to the rotation ring 370 through the teeth 374,376, the rotation motor being connected to the rock drill chamber 12 in a manner as hereinabove described.

Finally, FIG. 8 illustrates an arrangement wherein a pilot operated four way valve is utilized for motivating the clutch actuator. In this arrangement, a pilot operated four way valve 400 is interposed between the main air supply line as controlled by throttle valve 46 and the clutch actuator, the valve 400 being shown as including a spool 402 provided with annular recesses 404,406 for selectively communicating the fluid pressure line 394 or the exhaust lines 408,410 with the lines 396,398 which lead to the opposite faces of the clutch actuating piston 478,480. As shown, the spool 402 is actuated by fluid pressure alternately supplied through lines 390,392 cornmunicating with opposite sides of the piston 14 at the rear and forward portions of the displacement chamber 12. In this arrangernent, the air used to actuate the rotation piston is derived directly from the air supply and need not pass through the automatic valve of the rock drill. While the pilots of the four way valve 400 in the present instance have been shown as being actuated by pressure from the front and rear ends of the piston displacement chamber, this valve 400 may be actuated by providing only a single port into either the front or rear hammer piston chamber and utilizing a spring for returning the valve to its second position. Also, the rotation piston 478,480 may be returned by a constant, air supply admitted to the annular space between the large and small diameter pistons as shown by dottedlines in FIG. 8.

lclaim:

1. In a fluid-actuated percussive tool comprising a power cylinder 12, tool-impacting piston 14 subdividing the power cylinder into a power stroke chamber and a return stroke chamber, said piston being arranged for reciprocating movement across an intermediate fluid vent opening means 60 which alternately connect with the two chambers, and power pulse valve means 38 for alternately admitting pressure fluid to the different cylinder chambers to thus move the piston so that spent fluids are exhausted through the intermediate vent opening means from alternate ones of the chambers: the improvement comprising overriding clutch means 70 for imparting one way rotary motion to the tool on every other stroke of the impacting piston, a timing cylinder (84 or 400), a reciprocatory clutch control piston (80, 180, 280 or 402) subdividing the timing cylinder into a clutch advance chamber and clutch slip chamber, a first passage between the power stroke chamber of cylinder 12 and one of the timing cylinder chambers, and a second passage between the return stroke chamber of cylinder 12 and the other one .of the timing cylinder chambers; each passage being effective to alternately act as a pressure supply passage for the clutch control piston and as a vent passage for the clutch control piston; the timing cylinder chambers being blind except for the first and second facing the clutch slip chamber.

3. The tool of claim 2 wherein the first passage connects the power stroke chamber of cylinder 12 with the clutch advance chamber of the timing cylinder, and the second passage connects the return stroke chamber of cylinder 12 with the clutch slip chamber of the timing cylinder.

takes the form of a piston type diverter valve 402 having a first fluid supply connection 394 with a source of pressure fluid and second fluid use connections 396 and 398 with the clutch,

5. The tool of claim 4 wherein each fluid use connection (396 or 398) is provided with an exhaust port (410 or 408), said diverter valve being shiftable so that the supply connection alternately shifts from one use connection to the other use connection while the exhaust port is shifting from the other use connection to the one use connection, and vice versa. 

